The present invention relates to an electronic whiteboard, and in particular to an electronic whiteboard system where the image of a PC screen projected onto a screen of the electronic whiteboard can be operated with a pen.
In recent years, an electronic whiteboard system is known incorporating a so-called interactive feature which uses a coordinate detection technology to automatically detect an operating position of an electronic whiteboard on a screen by using a sensor to project the screen of a computer unit such as a PC on the electronic whiteboard screen with a projector, so as to operate the image of the PC screen on the electronic whiteboard screen.
At the same time, by using software on a PC having a feature for directly drawing free lines on the image of a PC screen, it is possible to make an effective presentation.
Operation of a related art electronic whiteboard will be described referring to FIGS. 10, 11 and 12.
FIG. 10 is an explanatory drawing of a related art electronic whiteboard system, FIG. 11 an explanatory drawing showing the projected position information in the electronic whiteboard system in FIG. 10, FIG. 12 an explanatory drawing showing a drawing tool of software on the PC in the electronic whiteboard system in FIG. 10.
As shown in FIG. 10, in a related art electronic whiteboard system, an electronic whiteboard 101 and a PC (computer unit) 102 are interconnected via a communications cable 103a. A projector 104 for projecting the image of a screen 105 of a PC 102 onto a screen 111 the electronic whiteboard 101 and the PC 102 are interconnected via a communications cable 103b. Also provided are an electronic pen 107 for writing predetermined data onto the screen 111 where the image of the PC screen 105 is projected and coordinate detection sensors 106 arranged in two upper corners of the screen for detecting a coordinate position as a write position of the electronic pen 107 on the screen 111.
A coordinate detection technology required for an interactive feature in such an electronic whiteboard system will be described.
Infrared rays and a supersonic wave simultaneously issued from the electronic pen 107 are received by the coordinate detection sensor 106 and its time difference is used to calculate the distance from the electronic pen 107 to the coordinate detection sensor 106. That is, the distance between the two coordinate detection sensors 106 arranged in two upper corners of the screen 111 is known and a coordinate is detected via the trigonometry.
While coordinate detection on the screen 111 is made using the electronic pen 107 and the coordinate detection sensor 106, other coordinate detection technology such as a touch-panel system may be used. While the electronic whiteboard 101 and the PC 102, and the PC 102 and the projector 104 are connected by wires using communications cables 103a, 103b, radio communications may be used instead.
Coordinate information detected is sequentially sent to the PC 102 via the communications cable 103a. The PC 102 converts a coordinate assuming the upper left corner of the screen 111 to the coordinate system of the screen 105 of the PC 102, based on the received coordinate information.
The image of the screen 105 of the PC 102 is projected in an arbitrary position of the screen 111, so that it is necessary to know the projection position in advance. This is made possible by specifying the four corners of the image of the screen 105 on the screen 111 once when the projection position of the image of the screen 105 on the screen 111 is determined.
A range of the screen 111 shown in FIG. 11 is a projection area 112 of the image of a screen 105.
With the operation of specifying the four corners, the values of left, top, width, height are determined and stored. By associating a position where the electronic pen 107 is operated on the screen 111 to a position in the coordinate system of the PC 102, mouse event information can be generated in this position by way of software. This makes it possible to operate, on the screen 111, the image of the screen 105 of the PC 102 projected onto the screen 111.
When an arrow 121 is selected in the first drawing tool shown in FIG. 12, an ordinary mouse operation is allowed on the screen 111. When a pen 122 is selected, operating an electronic pen 107 on the image of the screen 105 of the screen 111 draws free lines on the image of the screen 105 to then locus of the operation. When an eraser 123 is selected, the same operation erases the free lines drawn with the pen 122. Pen Setting 124 is a button for changing the size and color of the pen 122. When Pen Setting 124 is selected, the size and color of the pen 122 is set for example by displaying a dialog box. Once setting is made, free lines are drawn with the pen 122 in specified size and color.
According to the electronic whiteboard system, it is possible to make an effective presentation by entering annotation in a necessary material with the pen 122 by using this system, with the image of the screen 105 of the PC 102 projected onto the screen of the electronic whiteboard 101.
In a related art electronic whiteboard system of the aforementioned configuration, a capture image of the screen 105 of the PC 102 where free lines are drawn is acquired as required and filed for storage as minutes of the proceedings.
However, the filed image is a still image obtained when capture of the screen 105 is specified and the stroke of the locus of the free lines therein cannot be referenced.